As used in the present disclosure, the following words and phrases are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used to indicate otherwise.
Biomass:
The term biomass in the context of the present disclosure means material such as algae and aquatic biomass, organic waste, urban refuse, wood, agricultural crops or wastes, municipal wastes and the like.
Crude Bio-Oil:
The term crude bio-oil used in the context of the present disclosure means an oil or biofuel derived from biomass and which can be used as an alternative to petroleum fuel.
Biomass, a renewable energy source, can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuels. Biofuels are derived from biomass and are intended to provide an alternative to petroleum fuels. Conversion of biomass into biofuel can be achieved by different methods which are broadly classified into thermal, chemical and biochemical methods. Biomass comprising algae and other aquatic biomass, is a resource that shows promise for advanced biofuels because of its higher photosynthetic efficiency, faster growth rate, and higher area-specific yield relative to terrestrial biomass.
Fossil fuels such as petroleum, natural gas and coal are typically formed through the processes of thermochemical conversion (TCC) from biomass buried beneath the ground.
TCC is a chemical reforming process of biomass in a heated and usually pressurized, oxygen deprived enclosure, where long-chain organic compounds break into short-chain hydrocarbons such as syngas or oil. TCC is a broad term that includes gasification, including the Fisher-Tropsch process, direct liquefaction, hydrothermal liquefaction and pyrolysis.
Pyrolysis is a heating process of dried biomass to directly produce syngas and/or oil. Both gasification and pyrolysis require dried biomass as feedstock and the processes occur in an environment higher than 600° C.
Hydrothermal liquefaction (HTL) is a technology for converting high-moisture waste biomass into energy dense “crude bio-oil” (CBO) that can be used for direct combustion or refined for transportation grade fuels.
HTL, also called hydrous pyrolysis, is a process for the reduction of complex organic materials such as bio-waste or biomass into crude oil and other chemicals.
Hydrothermal Liquefaction (HTL) technique, which involves the application of heat and pressure on a biomass medium, has an advantage that lipids and other organic components can be efficiently converted while the biomass is in wet condition. During HTL, high moisture biomass is subjected to elevated temperature (250-400° C.) and pressure (up to 225 bars) in order to break down and reform the chemical building blocks into crude bio-oil (CBO). HTL of biomass gives only crude bio-oil that needs to be further treated/refined to get the finished crude oil products. The hydrothermal process breaks down bio macromolecules in the wet biomass and promotes heteroatom removal.
WO2010030196 suggests the use of a phosphate catalyst for hydrothermal conversion of biomass into crude bio-oil (CBO). Although the products formed from the process are useful, the recovery of the catalyst used in the process is difficult and fresh catalyst needs to be added to each reaction. Also, the phosphate catalyst usually operates at a pH greater than 7, which may have a limiting action on the product range. Metal oxides are also known to provide catalytic activity for the conversion of biomass to CBO; these again use basic conditions and there are costs associated with the recovery of the catalyst.
There is, therefore, a need to develop a catalyst assisted process for the conversion of biomass to crude bio-oil (CBO), wherein the catalysts can be recovered and recycled; and the CBO so produced is compatible with petroleum crude used in the refinery process.